Once a phone number is ported to Twilio, it will have the same functionality as any equivalent number you purchase directly from Twilio. The ported number will be charged to your project on a monthly basis, just like a regular Twilio number.
To view specific phone number pricing for your country, you can refer to Twilio's pricing page. Please be informed that the one-time porting fee is applicable when the number is ported into Twilio, whereas porting pricing is different. When a US number is ported into our network, there is no porting fee.
There will be a one-time porting fee for non-US numbers while the number is porting, followed by ongoing monthly fees based on usage once the number is ported into our network.
If you have any questions about the porting process, please contact us at porting@twilio.com